JP2005274309A - Three-dimensional object inspection method and inspection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a high precision component floating inspection and bump shape inspection.
A method for inspecting a three-dimensional object arranged on a plate-like object, the step of obtaining an image obtained by imaging a three-dimensional object from a direction in which a side surface is projected using a wide-angle lens; And inspecting the three-dimensional object based on an image. In this way, by using a wide-angle lens, the same effect as when observed from an oblique direction can be obtained just by observing from the vertical direction, and the side of the part or the tip of the bump that has a needle shape can be observed. It is possible to inspect the float of components and the shape of bumps.
[Selection] Figure 1

Description

  The present invention is used for inspection of a mounting state of a component mounted on a circuit board or appearance inspection of a component before mounting. The mounted component is in a target state or the appearance shape of the component before mounting. More specifically, the illumination, the optical system, the imaging device, and the processing method of the captured image used when determining whether or not the component is in an appropriate state, more specifically, floating of a component that causes a problem in bonding failure or bonding strength, The present invention relates to a method for determining the shape of a bump formed on an IC chip with higher accuracy.

  With the recent trend toward smaller, lighter and more functional electrical products, there has been an increasing demand for smaller components and more components mounted at high density in the manufacture of circuit boards, which are the main components of electrical products. As the density increases, the component interval becomes narrower. Therefore, a short circuit is likely to occur due to the solder bridges and solder balls between the component terminals being connected to each other. The short circuit between the terminals makes the operation of the circuit unstable and a desired function cannot be realized. Therefore, preventing a short circuit between terminals is a very important issue.

  Further, with the miniaturization of parts, the influence of external force applied to the parts by the solder fluid increases. As a result, the mounting posture of components is becoming unstable. In particular, the floating of the component changes the shape and configuration of the solder at the joint, so the electrical characteristics deteriorate due to changes in electrical resistance, capacitance, inductance, etc. It causes a dynamic change and causes the operation to become unstable. In addition, due to the floating of the components, the bonding strength of the components is reduced, and it is impossible to secure the strength that can be released against vibration or external force. As described above, the floating of the component is a major cause of hindering stable circuit formation in the manufacture of the circuit board.

  Therefore, a method for measuring a circuit board three-dimensionally, inspecting the mounting state of a component, and finding and collecting a defect is disclosed (for example, see Patent Document 1). FIG. 12 is a diagram illustrating a configuration of an apparatus using the method described in Patent Document 1. In FIG. The apparatus shown in FIG. 12 irradiates slit light and linear light from directly above using a polygon laser. The apparatus measures the shape of the cut surface by observing the light beam from the direction rotated about the line direction (light cutting method).

  Further, a method using the fact that the amount of light passing through the pinhole is maximized when the focal point is matched is disclosed (for example, see Patent Document 2). FIG. 13 is a diagram illustrating a configuration of an apparatus that uses the method described in Patent Document 2. In FIG. The apparatus shown in FIG. 13 utilizes the fact that the amount of light passing through the pinhole is maximized when the focal point is matched, and scans the optical system in the vertical direction, from the amount of displacement of the optical system when the maximum amount of light is reached. Measure height (confocal method).

  In addition, a method using interference between white light and reflected light irradiated on a measurement target is disclosed (see Patent Document 3). FIG. 14 is a diagram showing a configuration of an apparatus using the method described in Patent Document 3. As shown in FIG. The apparatus shown in FIG. 14 measures the relative height of the determination target from the number of interference fringes using the interference between the white light and the reflected light irradiated on the determination target (white interference method).

Furthermore, because the joint surface is at the bottom of the part, such as BGA (Ball Grid Array) with balls or triangular pyramid bumps on the bottom surface of the IC, correction is physically impossible and the number of pins is large. Discloses a method for reducing the occurrence of component defects that are difficult to correct (see Patent Document 4). FIG. 15 is a diagram illustrating a configuration of an apparatus using the method described in Patent Document 4. In the apparatus shown in FIG. 15, the appearance of a component is inspected before mounting, and if there is an abnormality, that component is avoided and another component is mounted. Specifically, the device measures the position, presence or absence, flatness, etc. of the IC chip foot or bump, and mounts the component only when it is determined to be within a specified range by comparison with a reference value.
Japanese Patent Laid-Open No. 7-103733 JP 2000-275027 A JP 2001-66122 A JP 2001-124523 A

  However, since the conventional method has a limit in the diameter of the laser spot and the amount of incident light, it may be difficult to measure the distance between the parts as the part distance becomes narrower. Further, when there is a variation in the height of parts due to a problem in manufacturing accuracy, the conventional method may overlook the defective floating of the parts. FIG. 16 is a diagram for explaining the cause of missing a component floating failure. As shown in FIG. 16, when the height of the upper surface portion of the component is the same, the conventional method detects the difference between the reference height and the upper surface height as the detected height of the component. Therefore, in the conventional method, it is determined that the heights of the component a and the component b are the same, and it cannot be determined that the component b is floating. As described above, in the conventional method, the component floating failure is overlooked.

  In addition, as a problem that is particularly likely to occur in a film-like substrate, there is a problem that the floating of a component cannot be found when the substrate is warped. FIG. 17 is a diagram for explaining the reason why a component cannot be found due to warping of the board. As shown in FIG. 17, the height at the reference height measurement point does not match the height on the substrate surface around the component to be inspected due to the warp of the substrate. Therefore, when the component a is floating, it is determined that the upper surface of the component a and the upper surface of the component b are at the same height, and it is not determined that the component a is floating. As described above, even when the board is warped, the conventional method cannot detect the floating of the component.

  Such a problem is likely to occur when the reference height measurement point cannot be taken near the part. Setting a reference height measurement point may be difficult or impossible for a board in which parts are densely arranged. In order to ensure inspection accuracy, a lot of trial and error is required to set the reference height measurement point.

  Also, consider a case in which an abnormality in the shape of a bump formed on an IC is inspected using a conventional apparatus. The bump in the bonding method without leveling has a needle shape at the tip. Therefore, the light irradiated from the conventional apparatus is reflected on the bump surface, and the reflected light does not return to the sensor. Therefore, the conventional apparatus cannot measure the height of the bump having a needle-like tip. FIG. 18 is a diagram for explaining the reason why the height of a bump having a needle-like tip cannot be measured. As shown in FIG. 18, the light emitted from the light source is reflected by the bump, but since the tip of the bump has a needle shape, the reflected light does not return to the sensor.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method and apparatus capable of detecting a component floating defect in a circuit board mounting inspection with high accuracy. Another object of the present invention is to provide a method and an apparatus capable of measuring the height of a bump before leveling with high accuracy.

  In order to solve the above problems, the present invention has the following features. The present invention is a method for inspecting a three-dimensional object arranged on a plate-like object, the step of obtaining an image obtained by imaging a three-dimensional object from a direction in which a side surface is projected using a wide-angle lens; Inspecting a three-dimensional object based on the image.

  As described above, in the present invention, since a wide-angle lens is used, the same effect as when observed from an oblique direction can be obtained only by observing from the vertical direction, and the side surface of the component or the tip of the needle-like bump can be observed. It becomes possible to do. Therefore, it becomes possible to detect a gap between the bottom surface of the component and the board surface, and it is possible to prevent overlooking of floating defects due to variations in the height of the component and warping of the board, and in addition, Rather than detection based on the floating amount calculated virtually using the height and the standard height of the component, it is possible to directly detect the floating of the bottom surface of the component from the board surface, which is essential, and the accuracy of component floating failure detection Improvements can be made. In addition, it is possible to accurately measure the tip height of the needle-like bump.

  Preferably, in the step of inspecting the three-dimensional object, the position information obtained from the image is converted into the position information in the actual space according to the distortion characteristics of the wide-angle lens, and based on that, the three-dimensional object is inspected. Good.

  Preferably, in the step of acquiring an image, two images obtained by capturing a three-dimensional object from two positions are acquired, and in the step of inspecting the three-dimensional object, based on position information obtained from the two images, It is preferable to inspect the three-dimensional object by extracting the height information of the three-dimensional object in the actual space.

  Thereby, a perspective image can be easily obtained without tilting the imaging system, and an image with a large parallax can be obtained even when the viewing angle is small, and the height measurement accuracy can be improved.

  Specifically, the plate-like object is a substrate, and the three-dimensional object is a component arranged on the substrate, and in the step of acquiring an image, two images obtained by capturing the component from two positions In the process of inspecting the three-dimensional object, a pair of corresponding points corresponding to the bottom surface part of the part is searched between the two images, and the pair of corresponding points are found in the actual space according to the distortion characteristics of the wide-angle lens. Based on the principle of stereo vision, the coordinates of a pair of corresponding points obtained as a result of the coordinate conversion are converted into position information in the height direction, and based on the position information in the height direction. It is good to inspect whether the part is floating.

  Thereby, it becomes possible to measure the distance between the board surface and the bottom surface of the component, and it is possible to prevent an oversight of a floating defect due to a variation in the height of the component or a warp of the substrate. In addition, it is possible to directly detect the floating of the bottom of the component from the board surface, not the detection based on the virtually calculated floating amount using the relative height between the top surface of the component and the substrate surface and the standard height of the component. It is possible to improve the accuracy of detecting a component floating failure.

  Further, specifically, the plate-like object is a substrate, and the three-dimensional object is a component arranged on the substrate, and in the step of acquiring an image, two images obtained by imaging the component from two positions In the step of acquiring the image of the three-dimensional object and inspecting the three-dimensional object, a pair of corresponding points corresponding to the bottom portion of the part is searched between the two images, and the coordinates of the pair of corresponding points are based on the principle of stereo vision. The position information in the height direction is converted to the position information in the height direction in the actual space according to the distortion characteristics of the wide-angle lens, and the result of the coordinate conversion is obtained. Based on the position information in the height direction, it may be inspected whether or not the component is floating.

  Thereby, it becomes possible to measure the distance between the board surface and the bottom surface of the component, and it is possible to prevent an oversight of a floating defect due to a variation in the height of the component or a warp of the substrate. In addition, it is possible to directly detect the floating of the bottom of the component from the board surface, not the detection based on the virtually calculated floating amount using the relative height between the top surface of the component and the substrate surface and the standard height of the component. It is possible to improve the accuracy of detecting a component floating failure.

  Specifically, the plate-like object is an IC, and the three-dimensional object is a bump formed on the IC. In the step of acquiring an image, two images obtained by imaging the bump from two positions are obtained. In the step of acquiring and inspecting the three-dimensional object, a pair of corresponding points corresponding to the bump vertex positions are searched between the two images, and the pair of corresponding points are found on the actual space according to the distortion characteristics of the wide-angle lens. The coordinates of a pair of corresponding points obtained as a result of the coordinate conversion are converted into position information in the height direction based on the principle of stereo vision, and bumps are generated based on the position information in the height direction. It is good to inspect whether the height of is normal.

  Thereby, the height of the bump can be inspected with high accuracy.

  Preferably, in the step of acquiring an image, a single image obtained by capturing a three-dimensional object from one position is acquired, and in the step of inspecting the three-dimensional object, position information obtained from the single image is obtained using a wide-angle lens. According to the distortion characteristics, the information is converted into position information in an actual space, and a three-dimensional object is inspected based on the converted position information.

  Specifically, the plate-like object is an IC, and the three-dimensional object is a bump formed on the IC. In the step of acquiring an image, the bump is imaged from a position where the outline of the bump becomes clear. In the process of acquiring a single image and inspecting a three-dimensional object, the image is converted into an image in which the bump is viewed from the side according to the distortion characteristics of the wide-angle lens. The shape should be inspected.

  This makes it possible to capture the outline of all the bumps in perspective and reduce the inspection tact, as well as high accuracy even for unprocessed bumps with pointed tips that were difficult in the past. Therefore, the shape can be measured and more accurate inspection can be performed.

  More specifically, in the step of inspecting the shape of the bump based on the image after conversion, if the contour length of the apex portion of the bump is larger than a predetermined threshold, the head length of the bump is poor. It is good to determine that there is.

  More specifically, in the step of inspecting the shape of the bump based on the converted image, if the curvature of the apex portion of the bump is smaller than a predetermined threshold value (the sharpness is small), It may be determined that the tip shape is defective.

  The present invention is an inspection apparatus for inspecting a three-dimensional object arranged on a plate-like object, and includes a wide-angle lens, an imaging unit that captures an image of a subject obtained through the wide-angle lens, and an imaging unit And a control device for inspecting the three-dimensional object based on the image obtained by imaging the three-dimensional object from the direction in which the side surface is projected.

  Preferably, the control device may convert position information obtained from the image into position information in an actual space according to the distortion characteristics of the wide-angle lens, and inspect the three-dimensional object based on the converted position information.

  Preferably, the control device causes the imaging unit to acquire two images obtained by imaging the three-dimensional object from two positions, and based on the position information obtained from the two images, the three-dimensional object in the actual space. It is preferable to inspect a three-dimensional object by extracting height information.

  Specifically, the plate-like object is a substrate, the three-dimensional object is a component arranged on the substrate, and the control device captures two images obtained by imaging the component from two positions. In accordance with the distortion characteristics of the wide-angle lens, the two-image acquisition means to be acquired, the corresponding point search means for searching for a pair of corresponding points corresponding to the bottom portion of the component, between the two images acquired by the two-image acquisition means The coordinate conversion means for converting the pair of corresponding points searched by the corresponding point search means into coordinates in the actual space, and the coordinates of the pair of corresponding points obtained as a result of the coordinate conversion by the coordinate conversion means are based on the principle of stereo vision Based on the height information acquisition means for converting into position information in the height direction based on the position information in the height direction obtained by the height information acquisition means, the floating inspection for inspecting whether or not the component is floating Means.

  Specifically, the plate-like object is a substrate, the three-dimensional object is a component arranged on the substrate, and the control device captures two images obtained by imaging the component from two positions. The two-image acquisition means to be acquired, the corresponding point search means for searching for a pair of corresponding points corresponding to the bottom portion of the component, and the corresponding point search means searched between the two images acquired by the two-image acquisition means Height information acquisition means for converting the coordinates of a pair of corresponding points into position information in the height direction based on the principle of stereo vision, and the height direction obtained by the height information acquisition means according to the distortion characteristics of the wide-angle lens The coordinate conversion means for converting the position information of the position into the position information in the height direction in the actual space, and the part floating based on the position information in the height direction obtained as a result of the coordinate conversion by the coordinate conversion means Floating inspection means to inspect whether or not It may contain.

  Specifically, the plate-like object is an IC, the three-dimensional object is a bump formed on the IC, and the control device captures two images obtained by imaging the bump from two positions in the imaging unit. Corresponding according to the distortion characteristics of the wide-angle lens, the two-image acquisition means to be acquired, the corresponding point search means for searching for a pair of corresponding points corresponding to the vertex positions of the bumps between the two images acquired by the two-image acquisition means Based on the principle of stereo vision, the coordinate conversion means for converting the pair of corresponding points searched by the point search means into coordinates in the actual space, and the coordinates of the pair of corresponding points obtained as a result of the coordinate conversion by the coordinate conversion means Based on the height information acquisition means for converting the position information in the height direction and the position information in the height direction obtained by the height information acquisition means, whether or not the bump height is normal is inspected. Including bump height inspection means Good.

  Preferably, the control device causes the imaging unit to acquire a single image obtained by imaging a three-dimensional object from one position, and obtains position information obtained from the single image on an actual space according to the distortion characteristics of the wide-angle lens. It is preferable to inspect the three-dimensional object based on the converted position information.

  Specifically, the plate-like object is an IC, the three-dimensional object is a bump formed on the IC, and the control device causes the imaging unit to pick up the bump from a position where the outline of the bump becomes clear. According to one image acquisition means for acquiring one image, an image conversion means for converting the image acquired by the one image acquisition means into an image viewed from the side surface according to the distortion characteristics of the wide-angle lens, and an image conversion means Bump shape inspection means for inspecting the shape of the bump based on the image after conversion may be included.

  More specifically, the bump shape inspection means may determine that the head length of the bump is bad when the contour length of the apex portion of the bump is larger than a predetermined threshold value.

  More specifically, the bump shape inspection means may determine that the tip shape of the bump is defective when the curvature of the apex portion of the bump is smaller than a predetermined threshold value (the sharpness is small).

  As described above, according to the inspection method and inspection apparatus for a three-dimensional shape of the present invention, a perspective image that includes a large amount of side information of an inspection object easily without tilting the imaging system by using a wide-angle (fisheye) lens. Since a large parallax image can be obtained even for an object with a small viewing angle, height measurement accuracy can be improved.

  In addition, since the side of the component can be imaged, the gap length between the board surface and the bottom of the component can be measured, and it is easy to detect floating with high accuracy that is difficult to determine only by the height of the top surface due to component height variations and board warpage. It can be carried out.

  In addition, by taking an image of an IC bump with the same imaging unit and projecting the image taken from a position where the outline becomes clear with respect to the inspection target IC, high-speed bump outline shape measurement by collective imaging This makes it possible to shorten the inspection tact. Also, corresponding points of at least two images that have been imaged by moving in a plane direction or a vertical direction with respect to the inspection target IC are extracted, and projective transformation is performed using a transformation function according to the characteristics of the lens using the amount of displacement. Thus, not only the contour but also the height of each point can be measured with high accuracy.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each figure, about the part which has the same function, the same referential mark is attached | subjected and description is abbreviate | omitted.

(First embodiment)
In the first embodiment, an apparatus that can measure and determine the float of a component will be described. FIG. 1 is a diagram showing a schematic configuration of a mounting board inspection apparatus 100 according to the first embodiment of the present invention.

  In FIG. 1, a mounting board inspection apparatus 100 includes an imaging camera unit 1 for imaging an inspection target board 3 that is a plate-like object, and a wide-angle (also referred to as fisheye) lens for obtaining an image including a component side surface. 2 and a control device (not shown).

  The imaging camera unit 1 is fixed to a moving unit (not shown) for moving the imaging camera unit 1 in two directions in a direction parallel to the substrate plane and moving in one direction in a vertical direction. Therefore, the relative positional relationship between the imaging camera unit 1 and the inspection target substrate 3 can be changed three-dimensionally.

  FIG. 2 is a diagram showing an internal configuration of the mounting board inspection apparatus 100. In FIG. 2, the imaging camera unit 1 includes an imaging camera 4, an imaging optical system 5, a half mirror 6, a light source 7, and an illumination optical system 8.

  The light output from the light source 7 enters the half mirror 6 via the illumination optical system 8. The light incident on the half mirror 6 is reflected and incident on the imaging optical system 5. The imaging optical system 5 refracts the incident light so as to be condensed in the optical axis direction of the wide-angle lens 2. The light refracted by the imaging optical system 5 enters the wide-angle lens 2. The wide-angle lens 2 diffuses incident light. As a result, the wide-angle lens 2 irradiates the inspection target substrate 3 with wide-angle light.

  The light reflected from the inspection target substrate 3 is collected by the wide-angle lens 2 and refracted by the imaging optical system 5 so as to be condensed in the direction of the imaging camera 4. The light refracted by the imaging optical system 5 passes through the half mirror 6 and enters the imaging camera 4. The imaging camera 4 captures an image of a subject based on incident light and outputs an image. A control device is connected to the imaging camera 4.

  The control device typically includes a computer device, and determines whether the imaged component is floating from the board based on an image output from the imaging camera 4. The hardware configuration of the control device may be a dedicated LSI, or a configuration in which a dedicated program is executed by a general-purpose CPU.

  The wide-angle lens 2 plays two roles of illumination diffusion and wide-angle imaging.

  FIG. 3 is a diagram schematically showing a state in which the mounting board inspection apparatus 100 is moved left and right so as to be parallel to the inspection target board 3 and a state of a captured image output from the imaging camera unit 1 at that time.

  As shown in FIG. 3, when the imaging camera unit 1 is arranged at the upper part of the center between the components 3 a and 3 b on the inspection target substrate 3 (see (a)), the imaging camera unit 1 is output. The image to be displayed becomes an image 4a. Since the wide-angle lens 2 is used, as shown in the image 4a, an image showing the left side surface 3c of the component 3a and the right side surface 3d of the component 3b is output.

  When the imaging camera unit 1 is arranged in the upper direction of the component 3b on the inspection target substrate 3 (see (b)), an image output from the imaging camera unit 1 is an image 4b. Since the wide-angle lens 2 is used, as shown in the image 4b, an image showing the left side surface 3c of the component 3a and the right side surface 3d of the component 3b is output. In addition, when the wide-angle lens 2 is disposed immediately above the component 3b, the side surface 3d is not reflected.

  FIG. 4 is a diagram for specifically explaining an example of the inspection method according to the present embodiment. In FIG. 4, an image 4 a is an example of an image input to the control device when the imaging camera unit 1 is disposed at the center between the component 3 a and the component 3 b. The image 4b is an example of an image input to the control device when the imaging camera unit 1 is shifted in the upper direction of the component 3b. The image 4c schematically shows a state when the image 4a and the image 4b are superimposed on one image.

  In FIG. 4, it is assumed that the component 3a is floating from the board. As shown in the image 4c, when the component is floating, the boundary line indicating the bottom portion of the component is greatly deviated between the image captured from the center position between the components and the image slightly shifted in the board parallel direction. I understand. Therefore, the control device may check the amount of change in the bottom surface portion of the part of the two images obtained from the imaging camera 4 and determine that the part is floating if the amount of change is greater than a certain value. Thereby, it is possible to inspect whether or not the part is floating. In order to check whether or not the component 3b is floating, the imaging camera unit 1 is moved to the upper part of the component 3a so that the side surface of the component 3b can be imaged, and based on the amount of change in the bottom portion of the component 3b. Whether or not the part 3b is floating may be determined.

  FIG. 5 is a diagram for specifically explaining another example of the inspection method according to the present embodiment. In FIG. 5, an image 11a is an example of an image input to the control device when the imaging camera unit 1 is arranged at the center between the component 3a and the component 3b. The image 11b is input to the control device when the imaging camera unit 1 is arranged at the center between the component 3a and the component 3b and the imaging camera unit 1 is moved vertically downward from the imaging location of the image 11a. It is an example of the image to be performed. The image 11c schematically shows a state when the image 11a and the image 11b are superimposed on one image.

  In FIG. 5, it is assumed that the component 3a is floating from the substrate. It is assumed that the component 3b does not float from the substrate. As shown in the image 11c, when the component is floating, the boundary line indicating the bottom portion of the component is greatly shifted between the image captured from the center position between the components and the image shifted downward in the vertical direction of the board. I understand. On the other hand, as shown in the image 11c, when the component is not floating, the image captured from the center position between the components and the image shifted in the vertical downward direction of the board have a deviation amount of the boundary line indicating the bottom portion of the component, It turns out that there are few compared with the case where parts are floating. Therefore, the control device may check the amount of change in the bottom surface portion of the part of the two images obtained from the imaging camera 4 and determine that the part is floating if the amount of change is greater than a certain value. Thereby, it is possible to inspect whether or not the part is floating.

  FIG. 6 is a flowchart illustrating an example of a processing procedure in the control device. Hereinafter, an example of a processing procedure in the control device will be described with reference to FIG. 6, and an operation of the mounting board inspection device 100 will be described.

  First, the control device moves an imaging system (referring to the imaging-in-camera unit 1 and the wide-angle lens 2, hereinafter the same) to the vicinity of the center of the gap between the two parts for which floating detection is desired (step S101).

  Next, the control device causes the imaging camera 4 to capture the first image (step S102). An image obtained at this time is, for example, an image 4a. As a result, the control device obtains an image obtained by capturing a part, which is a three-dimensional object, disposed on the inspection target substrate 3 from the direction in which the side surface is projected.

  Next, the control device moves the imaging system by an amount that does not hide the edge in the direction perpendicular to the substrate plane with respect to the edge of the bottom surface of the component to be detected (step S103). At this time, if the control device moves the imaging system in a direction in which the side surface of the component is imaged more widely, the detection accuracy is further improved.

  Next, the control device causes the imaging camera 4 to capture a second image (step S104). An image obtained at this time is, for example, an image 4b.

  Next, the control device searches for a corresponding point of the edge portion on the bottom surface of a certain component among the two images obtained in steps S102 and S104, for example, using a pattern matching technique (step S105). ).

  Next, the control device converts the position information of the corresponding point of each image according to the distortion characteristics of the lens (step S106). Specifically, the control device captures a lattice pattern or the like in advance, creates a coordinate conversion table from a distorted image to a positive image, and coordinates position information of corresponding points according to the coordinate conversion table. The position information in the actual space is obtained by conversion. As a result, the corresponding point is converted from a coordinate system with lens distortion to a coordinate system in an actual space without lens distortion.

  When a certain point is seen from two different points, a point with a height causes a parallax, so the control device uses the difference in the position of the corresponding corresponding point as a parallax and uses the principle of stereo vision to determine the corresponding point. A position in the height direction is calculated, and the size of the calculated position in the height direction is set as a floating amount (step S107).

  Next, the control device determines whether or not the floating amount obtained in step S107 is larger than the maximum floating amount so far (step S108). The maximum floating amount is 0 in the initial operation.

  When it is larger than the maximum floating amount so far, the control device stores the calculated floating amount as the maximum floating amount (step S109), and proceeds to the operation of step S110. On the other hand, when it is not larger than the maximum floating amount so far, the control device directly proceeds to the operation of step S110.

  In step S110, the control device determines whether coordinate conversion for all corresponding points has been completed.

  If not completed, the control device returns to the operation of step S105 and continues the coordinate conversion for other corresponding points.

  On the other hand, when it is completed, the control device determines whether or not the maximum floating amount is larger than a predetermined threshold value (step S111). When the maximum floating amount is larger than a predetermined threshold value, the control device determines that the part corresponding to the corresponding point where the maximum floating amount is detected is floating and outputs that the part is floating. (Step S112), the process proceeds to Step S114. On the other hand, when the maximum floating amount is not larger than the predetermined threshold, the control device determines that the part corresponding to the corresponding point at which the maximum floating amount is detected is not floating, and the part is not floating. Is output (step S113), and the operation proceeds to step S114.

  In step S114, the control device determines whether or not corresponding points have been searched for all the components. When searching for corresponding points for all parts, the control device completes the floating detection process. On the other hand, when the corresponding points have not been searched for all the parts, the control device changes the parts for which the corresponding points are searched in step S105 (step S115), and returns to the operation of step S105.

  As described above, according to the first embodiment, a part that is a three-dimensional object is imaged from the direction in which the side surface is projected using the wide-angle (fisheye) lens, so that the imaging system is easily tilted without tilting. An image can be obtained. Therefore, even when the viewing angle is small, an image with a large parallax can be obtained, and the height measurement accuracy can be improved.

  Further, as shown in FIG. 7A, in the case of a lens that cannot capture the side surface of the component, such as a normal flat lens or a telecentric lens, or can only capture a small area, even if the stereo method is used, for example, the component It is impossible to measure heights other than those that can be observed from directly above, such as the upper surface or the upper surface of the solder ball. However, according to the present embodiment, the side surface of the component can be imaged as shown in FIG. 7B, so that the gap length between the substrate surface and the bottom surface of the component can be measured. Therefore, it is possible to easily detect the float that is difficult to judge with high accuracy.

  In the first embodiment, the coordinates of the corresponding points are converted, and then the height is detected using the principle of stereo vision. However, the parallax is calculated using the principle of stereo vision for the distorted image. After that, the actual height may be obtained by coordinate conversion. FIG. 8 is a flowchart illustrating a processing procedure in the control device in the case where the parallax is calculated with respect to the distorted image using the principle of stereo vision and then the coordinates are converted to obtain the actual height. Hereinafter, with reference to FIG. 8, the parallax is calculated for the distorted image using the principle of stereo vision, and then the processing procedure in the control device in the case of obtaining the actual height by performing coordinate conversion is described and implemented. The operation of the substrate inspection apparatus 100 will be described. In FIG. 8, parts having the same operations as the steps shown in FIG. 6 are denoted by the same step numbers and description thereof is omitted.

  After step S105, the control device calculates the position in the height direction using the principle of stereo vision, using the difference between corresponding point positions as the parallax in the distorted coordinate space (step S206). Note that the value obtained from this calculation result and the actual height are not in a linear relationship. Therefore, the value obtained from this calculation result is not proportional to the actual height.

  Next, the control device converts the obtained height in the distorted space into an actual height (step S207), and proceeds to the operation of step S108. Specifically, a wide-angle lens is used to determine the actual position of each lattice point that is distorted by using a lattice pattern or the like in advance so that the value obtained in step S206 is proportional to the actual height. Map transformation is performed based on a transformation map created by extracting grid points on the image and taking correspondence with actual grid points. Alternatively, a threshold value may be provided as it is without performing conversion.

  In the flowcharts shown in FIGS. 6 and 8, the control device moves the imaging system in a direction parallel to the substrate. However, even if the imaging system is moved in a direction perpendicular to the substrate, The floating of the part can be detected.

  Although the camera unit is moved here, the same effect can be obtained by moving the inspection target substrate. Here, height measurement is performed using only two images, but more images can be measured using more images.

(Second Embodiment)
In the second embodiment, an apparatus for inspecting the shape of a bump of an IC component will be described. FIG. 9 is a diagram showing a configuration of an IC bump shape inspection apparatus 200 according to the second embodiment of the present invention, an image captured by the IC bump shape inspection apparatus 200, and an image processed in the IC bump shape inspection apparatus 200. is there.

  In FIG. 2, an IC bump shape inspection apparatus 200 has an imaging camera unit 1 for imaging an inspection target IC 12 that is a plate-like object, and a wide angle for obtaining an image including many component side surfaces, as in the first embodiment. A (fisheye) lens 2 and a control device (not shown) are provided.

  The imaging camera unit 1 is fixed to a moving unit (not shown) having two axes in a direction parallel to the IC plane and one axis in a direction perpendicular thereto, so that the relative position with respect to the substrate can be changed three-dimensionally. Yes.

  The imaging camera unit 1 and the wide-angle (fisheye) lens 2 include a light source 7, an illumination optical system 8, a half mirror 6, and an imaging optical system 5, as shown in FIG. 2, as in the first embodiment. The wide-angle (fisheye) lens 2 plays two roles: illumination diffusion and wide-angle imaging.

  An image picked up by the IC bump shape inspection apparatus 200 becomes an image 13. The control device of the IC bump shape inspection apparatus 200 converts the image 13 into a planar image such as the image 14 by a conversion function described later. The image 14 is an image as seen from the side of a bump that is a three-dimensional object. Therefore, it is possible to inspect whether or not the shape of the tip portion of the bump is sharp.

  FIG. 10 is a flowchart illustrating an example of a processing procedure in the control device. Hereinafter, an example of a processing procedure in the control device will be described with reference to FIG. 10, and an operation of the IC bump shape inspection device 200 will be described.

  First, the control device moves the imaging system so that the optical axis of the wide-angle lens 2 is at the center of the inspection target IC (step S301).

  Next, the control apparatus brings the imaging system closer to the inspection target IC until a position where the silhouette of the bump to be inspected can be clearly observed (a position where the imaging target is reflected in the maximum size) (step S302). The observation angle formed by the vertical direction of the bump and the optical axis of the wide-angle lens 2 is preferably 45 degrees or more.

  Next, the control device causes the imaging camera 4 to capture an image (step S301).

  Next, the control device performs coordinate conversion of the obtained image into a regular image according to the distortion characteristics of the lens (step S304). Specifically, the control device uses a grid pattern or the like in advance, extracts the grid point on the wide-angle lens image to determine where each grid point that is distorted is actually located, and corresponds to the actual grid point Coordinate transformation is performed based on the transformation map created by taking.

  Next, the control device detects the bump position from the obtained image using, for example, pattern matching (step S305).

  Next, the control device extracts an outline relating to a certain bump using, for example, an edge detection filter (step S306).

  Next, the control device determines whether or not the contour length of the vertex portion is larger than a predetermined threshold value (step S307). If larger, the control unit outputs NG on the assumption that the length of the head portion of the bump is large (step S308), and proceeds to the operation of step S312. In this case, vertex formation due to crushing or the like is insufficient. On the other hand, if not, the control device proceeds to the operation of step S309.

  In step S309, the control device determines whether the curvature of the apex portion of the bump is larger than a predetermined threshold value. If larger, the control unit outputs OK, assuming that the tip shape of the bump is normal (step S310), and proceeds to the operation of step S312. On the other hand, if it is not large, the control unit outputs NG assuming that the tip shape of the bump is above due to crushing or falling (step S311), and proceeds to the operation of step S312.

  In step S312, the control device determines whether or not the inspection has been completed for all the bumps. If not completed, the control device changes the bump from which the contour is extracted (step S313), and returns to the operation of step S306. On the other hand, when it is completed, the control device ends the inspection.

  Note that the bump height may be detected using the principle of stereo vision. FIG. 11 is a flowchart showing a processing procedure in the control device that detects the height of the bump using the principle of stereo vision. In FIG. 11, steps having the same operations as those in the flowchart shown in FIG. 10 are denoted by the same step numbers and description thereof is omitted.

  After step S304, the control apparatus moves the imaging system in the substrate plane direction (or substrate vertical direction), and images the inspection target IC again (step S405).

  Next, the control device detects the vertex position of a certain bump in the obtained two images using, for example, a pattern matching method (step S406).

  Next, the control device performs coordinate conversion of the detected vertex position according to the distortion characteristics of the lens (step S407). Specifically, the control device images a lattice pattern or the like in advance, creates a coordinate conversion table from a distorted image to a positive image, and performs coordinate conversion according to the coordinate conversion table. Thereby, the positional information with distortion regarding the vertex position is converted into positional information in the actual space without distortion.

  Since the difference between the converted vertex positions becomes parallax, the control device next calculates the position in the height direction using the principle of stereo vision (step S408).

  Next, the control device determines whether or not the height obtained in step S408 is smaller than a predetermined threshold value (step S409). If not, the control device outputs OK as the bump height is normal (step S410), and proceeds to the operation of step S412. On the other hand, if it is smaller, the control device outputs NG on the assumption that the bump height is equal to or higher (step S411), and proceeds to the operation of step S412.

  In step S412, the control device determines whether or not the height inspection has been performed for all the bumps. If not, the control device changes the bump for detecting the vertex position (step S413), and proceeds to the operation of step S406. On the other hand, if it is, the control device ends the inspection.

  In the inspection method shown in FIG. 10 and / or FIG. 11, once NG is output, other bumps need not be inspected.

  As described above, according to the second embodiment, it is possible to perform high-speed bump contour shape measurement by batch imaging by performing projective transformation on an image captured from a position where the contour is clear with respect to the inspection target IC 12. Therefore, the inspection tact can be shortened.

  Further, by analyzing at least two images that are imaged by moving in the plane direction or the vertical direction with respect to the inspection target IC 12, a detailed three-dimensional shape of the bump can be measured, and a highly accurate bump shape inspection can be realized.

  Note that the inspection process shown in FIG. 10 and the inspection process shown in FIG. 11 may be performed simultaneously. As a result, the inspection tact can be shortened and a partial detailed inspection can be performed, so that a more accurate inspection can be performed.

  Here, the imaging camera unit 1 is moved, but the same effect can be obtained even if the inspection target IC 12 is moved. Here, height measurement is performed using only two images, but more images can be used and measurement can be performed with higher accuracy.

  The three-dimensional measurement method and apparatus of the present invention can easily obtain a perspective image including a lot of side information of an inspection object without tilting the imaging system by using a wide-angle (fisheye) lens, and is an object with a small viewing angle. Even in such a case, an image with a large parallax can be obtained, so that the height measurement accuracy can be improved.

  In addition, since the side of the component can be imaged, the gap length between the board surface and the bottom of the component can be measured, and it is easy to detect floating with high accuracy that is difficult to determine only by the height of the top surface due to component height variations and board warpage. It can be carried out.

  In addition, by taking an image of an IC bump with the same imaging unit and projecting the image taken from a position where the outline becomes clear with respect to the inspection target IC, high-speed bump outline shape measurement by collective imaging This makes it possible to shorten the inspection tact. Also, corresponding points of at least two images that have been imaged by moving in a plane direction or a vertical direction with respect to the inspection target IC are extracted, and projective transformation is performed using a transformation function according to the characteristics of the lens using the amount of displacement. Thus, not only the contour but also the height of each point can be measured with high accuracy.

  From the above points, the present invention can also be applied to uses such as printed solder shape inspection, mounting component inspection, post-mounting board inspection, and post-reflow board appearance inspection in mounting machines and inspection machines incorporated in production lines for electric / electronic circuit formation.

FIG. 1 is a diagram showing a schematic configuration of a mounting board inspection apparatus 100 according to a first embodiment of the present invention. The figure which shows the internal structure of the mounting board inspection apparatus 100 The figure which shows typically a mode that the mounted substrate test | inspection apparatus 100 is moved right and left so that it may become parallel to the test object board | substrate 3, and the mode of the captured image output from the imaging camera unit 1 at that time. The figure for demonstrating concretely an example of the inspection method concerning this embodiment The figure for demonstrating specifically the other example of the inspection method which concerns on this embodiment The flowchart which shows an example of the process sequence in a control apparatus The figure for demonstrating the effect of this invention The flowchart which shows the process sequence in a control apparatus in the case of calculating a parallax using the principle of a stereo vision with respect to a distortion image, and calculating | requiring actual height by performing coordinate conversion The figure which shows the structure of the IC bump shape inspection apparatus 200 which concerns on the 2nd Embodiment of this invention, the image which the IC bump shape inspection apparatus 200 images, and the image processed in the IC bump shape inspection apparatus 200 The flowchart which shows an example of the process sequence in a control apparatus Flow chart showing the processing procedure in the control device that detects the bump height using the principle of stereo vision The figure which shows the structure of the apparatus using the method described in patent document 1 The figure which shows the structure of the apparatus using the method described in patent document 2 The figure which shows the structure of the apparatus using the method described in patent document 3 The figure which shows the structure of the apparatus using the method described in patent document 4 Diagram for explaining the cause of missing parts floating failure Diagram for explaining why the component cannot be found due to warping of the board Diagram for explaining the reason why the height of a bump with a needle-like tip cannot be measured

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging unit 2 Wide angle lens 3 Inspection object board | substrate 4 Imaging camera 5 Imaging optical system 6 Half mirror 7 Light source 8 Illumination optical system 100 Mounting board inspection apparatus 200 IC bump shape inspection apparatus

Claims (20)

A method for inspecting a three-dimensional object arranged on a plate-like object,
Obtaining an image obtained by imaging the three-dimensional object from a direction in which a side surface is projected using a wide-angle lens;
And a step of inspecting the three-dimensional object based on the image.   In the step of inspecting the three-dimensional object, position information obtained from the image is converted into position information in an actual space according to distortion characteristics of the wide-angle lens, and the three-dimensional object is inspected based on the converted position information. The inspection method according to claim 1, wherein: In the step of acquiring the image, two images obtained by capturing the three-dimensional object from two positions are acquired,
In the step of inspecting the three-dimensional object, height information of the three-dimensional object in an actual space is extracted based on position information obtained from the two images, and the three-dimensional object is inspected. The inspection method according to claim 2, wherein: The plate-like object is a substrate;
The three-dimensional object is a component arranged on the substrate,
In the step of acquiring the image, two images obtained by capturing the part from two positions are acquired,
In the step of inspecting the three-dimensional object,
Search between a pair of corresponding points corresponding to the bottom portion of the part between the two images,
In accordance with the distortion characteristics of the wide-angle lens, the pair of corresponding points are coordinate-transformed into coordinates in actual space,
Based on the principle of stereo vision, the coordinates of a pair of corresponding points obtained as a result of the coordinate conversion are converted into position information in the height direction,
The inspection method according to claim 3, wherein whether or not the component is floating is inspected based on position information in the height direction. The plate-like object is a substrate;
The three-dimensional object is a component arranged on the substrate,
In the step of acquiring the image, two images obtained by capturing the part from two positions are acquired,
In the step of inspecting the three-dimensional object,
Search between a pair of corresponding points corresponding to the bottom portion of the part between the two images,
Based on the principle of stereo vision, the coordinates of the pair of corresponding points are converted into position information in the height direction,
According to the distortion characteristics of the wide-angle lens, the position information in the height direction is coordinate-transformed into position information in the height direction on the actual space,
The inspection method according to claim 3, wherein whether or not the component is floating is inspected based on position information in a height direction obtained as a result of the coordinate conversion. The plate-like object is an IC;
The three-dimensional object is a bump formed on the IC,
In the step of acquiring the image, two images obtained by capturing the bump from two positions are acquired,
In the step of inspecting the three-dimensional object,
Search for a pair of corresponding points corresponding to the vertex positions of the bumps between the two images,
In accordance with the distortion characteristics of the wide-angle lens, the pair of corresponding points are coordinate-transformed into coordinates in actual space,
Based on the principle of stereo vision, the coordinates of a pair of corresponding points obtained as a result of the coordinate conversion are converted into position information in the height direction,
The inspection method according to claim 3, wherein whether or not the height of the bump is normal is inspected based on position information in the height direction. In the step of acquiring the image, one image obtained by capturing the three-dimensional object from one position is acquired;
In the step of inspecting the three-dimensional object, position information obtained from the one image is converted into position information on an actual space according to the distortion characteristics of the wide-angle lens, and based on the position information, the three-dimensional object is converted. The inspection method according to claim 2, wherein an object is inspected. The plate-like object is an IC;
The three-dimensional object is a bump formed on the IC,
In the step of acquiring the image, the bump is imaged from a position where the outline of the bump is clear, and one image is acquired.
In the step of inspecting the three-dimensional object,
According to the distortion characteristics of the wide-angle lens, the image is converted into an image of the bump viewed from the side,
The inspection method according to claim 7, wherein the shape of the bump is inspected based on the image after conversion.   In the step of inspecting the shape of the bump based on the image after conversion, when the contour length of the apex portion of the bump is larger than a predetermined threshold, it is determined that the head length of the bump is defective. The inspection method according to claim 8, wherein:   In the step of inspecting the shape of the bump based on the image after conversion, if the curvature of the apex portion of the bump is smaller than a predetermined threshold value, it is determined that the tip shape of the bump is defective. The inspection method according to claim 8, wherein: An inspection apparatus for inspecting a three-dimensional object arranged on a plate-like object,
A wide-angle lens,
An imaging unit that captures an image of a subject obtained through the wide-angle lens;
An inspection apparatus comprising: a control device that causes the imaging unit to image the three-dimensional object from a direction in which a side surface is projected, and inspects the three-dimensional object based on an image obtained thereby.   The control device converts position information obtained from the image into position information in an actual space according to distortion characteristics of the wide-angle lens, and inspects the three-dimensional object based on the position information. The inspection apparatus according to claim 11. The control device includes:
Two images obtained by imaging the three-dimensional object from two positions are acquired by the imaging unit,
13. The three-dimensional object is inspected by extracting height information of the three-dimensional object in an actual space based on position information obtained from the two images. The inspection device described. The plate-like object is a substrate;
The three-dimensional object is a component arranged on the substrate,
The control device includes:
Two-image acquisition means for causing the imaging unit to acquire two images obtained by imaging the component from two positions;
Corresponding point search means for searching for a pair of corresponding points corresponding to the bottom surface portion of the part between the two images acquired by the two image acquisition means;
Coordinate conversion means for converting the pair of corresponding points searched by the corresponding point search means into coordinates in an actual space according to the distortion characteristics of the wide-angle lens;
Height information acquisition means for converting the coordinates of a pair of corresponding points obtained as a result of the coordinate conversion by the coordinate conversion means to position information in the height direction based on the principle of stereo vision;
The inspection apparatus according to claim 13, further comprising: a float inspection unit that inspects whether or not the component is floating based on position information in the height direction obtained by the height information acquisition unit. The plate-like object is a substrate;
The three-dimensional object is a component arranged on the substrate,
The control device includes:
Two-image acquisition means for causing the imaging unit to acquire two images obtained by imaging the component from two positions;
Corresponding point search means for searching for a pair of corresponding points corresponding to the bottom surface portion of the part between the two images acquired by the two image acquisition means;
Height information acquisition means for converting the coordinates of the pair of corresponding points searched by the corresponding point search means into position information in the height direction based on the principle of stereo vision;
Coordinate conversion means for converting the position information in the height direction obtained by the height information acquisition means into position information in the height direction on the actual space according to the distortion characteristics of the wide-angle lens;
The inspection apparatus according to claim 13, further comprising: a float inspection unit that inspects whether or not the component is floating based on position information in a height direction obtained as a result of coordinate conversion by the coordinate conversion unit. The plate-like object is an IC;
The three-dimensional object is a bump formed on the IC,
The control device includes:
Two-image acquisition means for causing the imaging unit to acquire two images obtained by imaging the bump from two positions;
Corresponding point search means for searching for a pair of corresponding points corresponding to the vertex positions of the bumps between the two images acquired by the two image acquisition means;
Coordinate conversion means for converting the pair of corresponding points searched by the corresponding point search means into coordinates in an actual space according to the distortion characteristics of the wide-angle lens;
Height information acquisition means for converting the coordinates of a pair of corresponding points obtained as a result of the coordinate conversion by the coordinate conversion means into position information in the height direction based on the principle of stereo vision;
The bump height inspection means for inspecting whether or not the height of the bump is normal based on the position information in the height direction obtained by the height information acquisition means. Inspection equipment. The control device includes:
Causing the imaging unit to acquire one image obtained by imaging the three-dimensional object from one position;
The positional information obtained from the single image is converted into positional information on an actual space according to the distortion characteristics of the wide-angle lens, and the three-dimensional object is inspected based on the converted positional information. The inspection apparatus according to claim 12. The plate-like object is an IC;
The three-dimensional object is a bump formed on the IC,
The control device includes:
One image acquisition means for causing the imaging unit to image the bump from a position where the outline of the bump is clear, and acquiring one image;
In accordance with the distortion characteristics of the wide-angle lens, the image conversion unit that converts the image acquired by the one image acquisition unit into an image of the bump viewed from a side surface;
The inspection apparatus according to claim 17, further comprising: a bump shape inspection unit that inspects the shape of the bump based on an image converted by the image conversion unit.   The bump shape inspection means determines that the head length of the bump is defective when the contour length of the apex portion of the bump is larger than a predetermined threshold value. The inspection device described.   The bump shape inspection means determines that the tip shape of the bump is defective when the curvature of the apex portion of the bump is smaller than a predetermined threshold value. Inspection equipment.

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